A power conversion efficiency (PCE) as high as 19.7% is achieved using a novel, low‐cost, dopant‐free hole transport material (HTM) in mixed‐ion solution‐processed perovskite solar cells (PSCs). ...Following a rational molecular design strategy, arylamine‐substituted copper(II) phthalocyanine (CuPc) derivatives are selected as HTMs, reaching the highest PCE ever reported for PSCs employing dopant‐free HTMs. The intrinsic thermal and chemical properties of dopant‐free CuPcs result in PSCs with a long‐term stability outperforming that of the benchmark doped 2,2′,7,7′‐Tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐Spirobifluorene (Spiro‐OMeTAD)‐based devices. The combination of molecular modeling, synthesis, and full experimental characterization sheds light on the nanostructure and molecular aggregation of arylamine‐substituted CuPc compounds, providing a link between molecular structure and device properties. These results reveal the potential of engineering CuPc derivatives as dopant‐free HTMs to fabricate cost‐effective and highly efficient PSCs with long‐term stability, and pave the way to their commercial‐scale manufacturing. More generally, this case demonstrates how an integrated approach based on rational design and computational modeling can guide and anticipate the synthesis of new classes of materials to achieve specific functions in complex device structures.
Highly‐efficient, low‐cost, solution‐processed perovskite solar cells, exhibiting remarkable environmental stability, are reported. The fabrication strategy relies on the rational design of the molecular structure of arylamine‐substituted copper(II) phthalocyanine (CuPc) derivatives, which are used as dopant‐free hole‐transport materials. The resulting devices reach a power conversion efficiency of 19.7% and display enhanced long‐term stability with respect to standard (doped) materials.
Digitalization is prompting small and medium-sized enterprises to structural and strategic transformations, also providing new opportunities to expand and succeed in foreign markets. However, ...relatively few studies have investigated emergent digital technologies in international business management. Contextually, there is still a dearth of research on the multi-faceted impacts of digitalization on omnichannel strategy characterizing most of the global business environment today. This paper, therefore, aims to examine the impact of digitalization on omnichannel choices adopted by internationalized SMEs. A qualitative approach, based on a single case study methodology, is adopted. An Italian agri-food SME is chosen as this industry is considered a key and distinctive pillar of Made in Italy in the international markets. Findings reveal the potential of digital technologies' applications in an omnichannel environment, blurring the boundaries between channels, through a synergetic integration of them. This evidence contributes to the existing literature on technology management and omnichannel strategies in the international context by rereading these phenomena through a smart ecosystem lens. In addition, this study provides practical insights on how multiple channels adopted by Made in Italy SMEs can be integrated, managed, and operated synergistically on international markets to sustain a digitalized value creation.
Organic field-effect transistors (OFETs) are key enabling devices for plastic electronics technology, which has a potentially disruptive impact on a variety of application fields, such as health, ...safety, and communication. Despite the tremendous advancements in understanding the OFET working mechanisms and device performance, further insights into the complex correlation between the nature of the charge-injecting contacts and the electrical characteristics of devices are still necessary. Here, an in-depth study of the metal–organic interfaces that provides a direct correlation to the performance of OFET devices is reported. The combination of synchrotron X-ray spectroscopy, atomic force microscopy, electron microscopy, and theoretical simulations on two selected electron transport organic semiconductors with tailored chemical structures allows us to gain insights into the nature of the injecting contacts. This multiple analysis repeated at the different stages of contact formation provides a clear picture on the synergy between organic/metal interactions, interfacial morphology, and structural organization of the electrode. The simultaneous synchrotron X-ray experiments and electrical measurements of OFETs in operando uncovers how the nature of the charge-injecting contacts has a direct impact on the injection potential of OFETs.
In this paper we discuss a Weierstrass type representation for minimal surfaces in the3-dimensional Heisenberg group and in the 4-dimensional Damek–Ricci spaces, endowed with left invariant ...Riemannian or Lorentzian metrics. For the case of spacelike surfaces we employ the complex analysis, and for timelike surfaces our approach makes use of the paracomplex analysis. Then, we exhibit various examples of spacelike and timelike minimal surfaces in these spaces.
Cytochrome P450 (CYP) monooxygenases catalyze the oxidation of chemically inert carbon–hydrogen bonds in diverse endogenous and exogenous organic compounds by atmospheric oxygen. This C–H bond ...oxy-functionalization activity has huge potential in biotechnological applications. Class I CYPs receive the two electrons required for oxygen activation from NAD(P)H via a ferredoxin reductase and ferredoxin. The interaction of Class I CYPs with their cognate ferredoxin is specific. In order to reconstitute the activity of diverse CYPs, structural characterization of CYP-ferredoxin complexes is necessary, but little structural information is available. Here we report a structural model of such a complex (CYP199A2-HaPux) in frozen solution derived from distance and orientation restraints gathered by the EPR technique of orientation-selective double electron–electron resonance (os-DEER). The long-lived oscillations in the os-DEER spectra were well modeled by a single orientation of the CYP199A2-HaPux complex. The structure is different from the two known Class I CYP-Fdx structures: CYP11A1-Adx and CYP101A1-Pdx. At the protein interface, HaPux residues in the Fe2S2 cluster-binding loop and the α3 helix and the C-terminus residue interact with CYP199A2 residues in the proximal loop and the C helix. These residue contacts are consistent with biochemical data on CYP199A2-ferredoxin binding and electron transfer. Electron-tunneling calculations indicate an efficient electron-transfer pathway from the Fe2S2 cluster to the heme. This new structural model of a CYP-Fdx complex provides the basis for tailoring CYP enzymes for which the cognate ferredoxin is not known, to accept electrons from HaPux and display monooxygenase activity.
The dynamics and energetics related to the release of chemisorbed hydrogen from small-diameter single-walled carbon nanotubes is investigated by first-principles molecular dynamics simulations. Our ...results suggest a possible route for thermally-activated desorption of hydrogen from the nanotube sidewall, leading to formation of molecular H2, and shed light on the basic mechanisms of the reversible storage of hydrogen in carbon nanotubes. In agreement with recent experiments, simulations indicate carbon nanotubes as suitable materials for the reversible storage of hydrogen. Moreover, calculations point to the restoration of the π bond patterning of the sidewall as the driving force for the desorption of hydrogen from carbon nanotubes.
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•Simulations reveal the mechanism of hydrogen release from carbon nanotubes.•High hydrogen coverages induce structural modifications of the sidewall.•First-principle molecular dynamics shed light on atomistic mechanisms.•Desorption is driven by the recovery of the pristine π-pattern of the sidewall.
Finite-length models of chiral semiconducting carbon nanotubes based on Clar sextet theory allowed carrying out accurate calculations, performed by application of gradient-corrected density ...functional theory, on the energetic of sidewall reactions. In particular, we analyzed the addition of atomic fluorine and carbene (CH2) to (6,4) and (6,5) nanotubes, finding excellent convergence of reaction energies with respect to the model length and good agreement with literature data. Our study demonstrates the importance of using models of carbon nanotubes based on chemical considerations to evaluate consistently the electronic and reactive properties of the sidewall.
Organic field‐effect transistors (OFETs) are considered almost purely interfacial devices with charge current mainly confined in the first two semiconducting layers in contact with the dielectric ...with no active role of the film thickness exceeding six to eight monolayers (MLs). By a combined electronic, morphological, structural, and theoretical investigation, it is demonstrated that the charge mobility and source–drain current in 2,20‐(2,20‐bithiophene‐5,50‐diyl)bis(5‐butyl‐5H‐thieno2,3‐cpyrrole‐4,6)‐dione (NT4N) organic transistors directly correlate with the out‐of‐plane domain size and crystallite orientation in the vertical direction, well beyond the dielectric interfacial layers. Polycrystalline films with thickness as high as 75 nm (≈30 MLs) and 3D molecular architecture provide the best electrical and optoelectronic OFET characteristics, highlighting that the molecular orientational order in the bulk of the film is the key‐enabling factor for optimum device performance. X‐ray scattering analysis and multiscale simulations reveal the functional correlation between the thickness‐dependent molecular packing, electron mobility, and vertical charge distribution. These results call for a broader view of the fundamental mechanisms that govern field‐effect charge transport in OFETs beyond the interfacial 2D paradigm and demonstrate the unexpected role of the out‐of‐plane domain size and crystallite orientation in polycrystalline films to achieve optimum electronic and optoelectronic properties in organic transistors.
Evidence is reported that the interfacial 2D paradigm used to describe the field‐effect charge transport in organic field‐effect transistors must be overcome. The out‐of‐plane molecular packing and orientational order in the bulk of polycrystalline films must be taken into account to design organic transistors with optimized electronic and optoelectronic properties.
Coordination of Vaska’s complex with a Stone–Wales defect on the sidewall of a carbon nanotube.
In this paper, our recent work concerning theoretical studies on the functionalization of carbon ...nanotubes (CNTs) is reviewed. In particular, two different aspects of the functionalization process are taken into account. On the one hand, the chemical functionalization of the sidewall is exploited as a way to develop nanostructured gas sensing devices. On the other hand, we investigated the possibility of functionalizing the sidewall with transition metal complexes, thus extending the concepts of organometallic chemistry to CNTs. Calculations were performed by applying statical and dynamical (Car–Parrinello) density functional theory methods, as well as hybrid (quantum mechanics/molecular mechanics) schemes. The structural and electronic peculiarities of the CNT model under study, due, for example to the presence of defects, were found to play a crucial role in the modelization of the functionalization process. In most cases, the use of realistic models was essential to achieve a full agreement with experiments.
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